Killer goldfish?

[AlexMason]

It is first time when i heard that Goldfish eat other ones in tank.

[oregonwoodsmoke]

Goldfish are really dirty fish. If you keep goldfish, you will need extensive filter systems plus frequent water changes. pH should be tested daily. Twice a day would be even better.

Inappropriate pH can kill the other plants and animals in your tank and will kill the goldfish, too, if it isn't corrected. If the pH is off, it can shred fins and cause skin diseases on the fish.

Goldfish aren't fancy guppies, where you can set it and forget it, maintaining the tank every couple of weeks.

Be careful to not feed more than they will clean up quickly and with enthusiasm. Uneaten food fouls the tank.

I've never had a goldfish kill anything else, with the exception of really small freshly hatched fish, that might get eaten because they are small enough to swallow. Disclaimer, though, I've never had common goldfish in a tank inside the house. But as pond fish, they don't kill each other.

[Jfish916]

I had a killer goldfish. He was a straight nut. I think he was insane. I won him from from one of those traveling fairs that come into town once a year. Maybe his experiences there were too much for his mind to take. When I won him from one of those games you play for a prize he along with many others were in tiny cages all lined next to each other. When we took him home put him in a 10 gallon tank he would zoom full speed around the tank so we named him Captain Frank. We went to pet store and got a couple more gold fish and those tiny guppy fish, and a sucker fish. The goldfish died but there bodys were torn. We saw him chasing the guppies but he could not catch them and they would go in small spaces he couldnt reach. He didnt seem to bother the sucker fish. Later we noticed at times when he was zooming around the tank some times he would ram the glass. He actually did it so hard that he stunned himself once for a couple seconds. At this point we wernt certain that Frank had killed the other fish. We bought a couple bug eyed chunky gold fish, one black and one orange. We found the orange one dead. One day me and my wife were looking into the tank and confirmed Frank was indeed a killer. We saw him kill the black goldfish. Frank swam and grabed the black goldfish and did an alligator like type of roll. The roll tore off one of his back fins. The black fish had difficulty swimming after that. Frank did it again and it nearly tore him in half. We couldnt believe it. After seeing this we decided not to put any more fish in the tank. Not long after that I think a week or two we found Frank dead. My guess is he ramed the glass again and killed himself by mistake. Maybe it was over frustration of not being able to get the guppies... not sure. What ever the case Frank was a homicidal maniac who terrorized the other poor fish in the tank. This is a true story. I asked google if anyone else had seen this because no one believes us when we tell them. Frank was one of those typical small orange gold fish you see in a small fish bowl.